(Revised Abstract) DESCRIPTION (provided by applicant): The Proteomics Shared Service (PSS) provides for the systematic analysis of proteins for their identity, quantity and function via state-of-the-art modern mass spectrometry and peripheral instrumentation, as well as through experienced personnel trained in the implementation of proteomic procedures, evaluation and interpretation of proteomics-related data. The PSS is supported jointly by the Arizona Cancer Center (AZCC) and the Southwest Environmental Health Sciences Center (SWEHSC) core grants. The objectives of the Proteomics Shared Service are to provide aid to AZCC and SWEHSC investigators as follows: In identifying and characterizing proteins and peptides and their modifications In implementing current proteomic protocols and methods when applicable; In designing proteomics experiments and interpreting data. The PSS is directed by George Tsaprailis, Ph.D., and staffed by one research specialist and one research technician, all supported by the AZCC and/or the SWEHSC core grants. Instrumentation in the Proteomics Shared Service includes a ThermoFinnigan TSQ-7000 triple quadruple mass spectrometer and a LCQ-Classic quadruple ion trap mass spectrometer, both equipped with electrospray and atmospheric pressure chemical ionization for HPLC-MS and HPLC-MS/MS work. These instruments are capable of high-sensitivity protein and peptide sequence analyses. Routine protein identification is also achieved via mass mapping of proteins with a Micromass MALDI-LR timeof- flight mass spectrometer. 1-D and 2-D gel electrophoresis and routine sample prep analyses are provided to users of the PSS. Instrument and procedure training is freely available and is encouraged for Proteomics Shared Service users. In addition, open-access workstations are available for data analysis. Chargeback fees for work performed in the PSS help to recover costs of instrument service contracts.